The research proposed herein evolved from years of experimentation with curarized rats in this laboratory -- research initiated to clarify the controversial issue of mediation as it applies to learned autonomic responding. A growing literature suggests that while neuromuscular blocking agents may still provide an effective research tool, they do not address themselves to the issue of centrally mediated effects. Moreover, generalizing to the normally functioning organism becomes, at best, hazardous. The fact that, at this point in time, previously reported effects in that preparation are not reproducible provides additional support for a change in direction with regard to autonomic learning in this species. The proposed research has as its ultimate objective an understanding of mechanisms involved in cardiovascular control in freely-moving rats. As a logical first step, it will focus upon the observation of relationships between the cardiovascular and somatomotor systems during either positive reinforcement of heart rate changes or positive reinforecement of activity changes. Since heart rate and blood pressure are very intimately related, it is proposed that these indices of cardiovascular activity be monitored continuously and compared with accompanying changes in two measures of somatomotor activity. Comparisons will be made between subjects provided with heart rate feedback and those not provided with such exteroceptive information of autonomic responding, as well as comparisons of effects achieved using positive vs. negative reinforcement procedures. In that regard, it is noteworthy that the largest heart rate effects ever achieved in curarized rats were accomplished using positive reinforcement. The initiation of the proposed direct blood pressure measure will represent a major focal point and should provide considerable insight into the mechanisms of heart rate change. It is further suggested that succinylcholine chloride be employed as a research tool in a transfer design to further define the mechanisms involved in cardiovascular control using instrumental techniques.